System and Method for Producing Dosing Bags that Are Filled with Dry Additives for Use in Cementitious Mixtures

ABSTRACT

A dosing bag filled with dry additive material is made using a dissolvable starch-based film. When the dosing bag with its contents are introduced into a mixture with water, it dissolves and releases its contents. The dosing bags are made in a chain. In this manner, any number of the dosing bags can be removed from the chain for use. The dosing bags are made from film material that is formed into a tube structure. While the tube structure is being partially filled, a section on the interior of the tube structure is shielded from contamination. After the partial filling, the tube is heat sealed closed in the area that was previously shielded. The shielded area is clean of contaminants and enables a high-quality seam to be formed. The shielding, filling, and sealing process is repeated multiple times to create the chain of dosing bags.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/237,916, entitled Dosing Bag Structure For Dispensing FiberAnd Admixtures into Cementitious Mixtures, filed Sep. 20, 2011.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the structure and manufacture ofprepackaged dosing bags that contain dry admixtures and/or fibers thatare intended to be added to cementitious mixtures.

2. Prior Art Description

Fibers and/or other admixture materials are often added to cementitiousproducts such as concrete.

Typically, fibers and/or admixture materials are added immediatelybefore or during the mixing of the cementitious product. Fibers and/oradmixture materials are used to improve or modify the cementitiousmaterial. Fibers and/or other admixture materials are used to modify theproperties of concrete in such a way as to improve the product, make theproduct more suitable for a particular purpose, or for economy. Theprimary reasons for using fibers and/or other admixture materials inconcrete are (1) to achieve certain properties in concrete moreeffectively than by other means; (2) to maintain a quality of concretethroughout the successive stages of mixing, transporting, placing, andcuring; (3) to overcome certain emergencies during concrete making orplacing operations; (4) to reduce the cost of concrete construction; and(5) to improve the mixture to control cracking or other detrimentaleffects.

In most instances the desired effect within the cementitious materialcan only be achieved by the use of fibers or admixture materials. Inaddition, the use of fibers and/or admixture allows for the use of lessexpensive construction methods or designs and thereby offsets the costsof the add materials. As an example, consider a mixing truck at the endof a delivery that still contains wet concrete within its mixer. If thewet concrete is left in the truck overnight, the residual product willset and begin to harden. While the wet concrete can be washed out of thetruck with a large amount of water, the disposal of the liquid may causean environmental problem. To avoid this problem, it is desirable todelay or retard the setting of concrete so that it remains fluid and canbe used the next day. This affect is achieved by adding a retardingadmixture to the wet concrete. However, an exact amount of the admixturehas to be added. If too much is added, the concrete will not properlycure the next day. If too little is added, the concrete may hardenprematurely.

Fibers and other concrete admixture materials are typically provided asfilaments, solids, or powders. As such, they must be mechanically mixedinto the concrete in order to be distributed. The more thorough themixing, the more uniform the fibers and/or admixture materials aredispersed. The successful use of these admixture materials depends uponthe accuracy with which they are prepared, the rate of which they aredispensed and the thoroughness of their distribution within the mixture.

Typically, concrete is made by weighing or volumetrically measuring theingredients for a batch and introducing all ingredients into a wetmixer. It is important that the amount of fibers and/or admixturematerial added during batching are carefully controlled. Inaccuracies inthe amount of fiber or admixture materials added or the thoroughness ofdispersion can significantly affect the properties and performance ofthe concrete products. The need for accuracy in measuring and havingeven dispersion of the amount of fibers or admixture materials to beadded to a particular batch are particularly acute when a relativelysmall amount of fibers or admixture materials are required for theproduct.

For fibers and/or admixture materials, it is cumbersome and timeconsuming to accurately weigh the required amount of additives. Thus,workers add fibers and/or admixtures to the concrete in pre-measured andpre-packaged bags. Such bags are known in the industry as dosing bags.The use of pre-measured dosing bags not only minimizes human error inhandling and weighing but it also facilitates the process of mixing theminto the product. One drawback of using dosing bags is that opening andemptying the pre-packaged dosing bags into the mixer creates a mess,wastes time, and results in some degree of spillage. The spillagecontributes to inaccuracies in batching. It also exposes workers tochemicals and dusts that are best not inhaled.

Another drawback in using prior art dosing bags is that the typicaldosing bags is made either from thin paper that is sealed with glue orwith a heat seal strip. Workers often just throw these bags into a mixwith no concern that the bag and the bag's seal will not dissolve intothe mix. If this debris is not physically removed, it can create flawsin the final concrete product. Furthermore, the additives stuck withinthe bag tend to get trapped in the bag and clump up. Extra mixing timemust therefore be used to ensure that the additives have the opportunityto disperse throughout the mixture.

Some attempts have been made to develop a dissolving dose bag fromdissolvable films such as polyvinyl acetate or polyvinyl alcohol (PVA).Such prior art dosing bags are exemplified by U.S. Pat. No. 4,961,790 toSmith, entitled Concrete Admixture Device and Method Of Using Same.However, such prior art dosing bags are highly sensitive to the humidityin the air. Thus, such prior art dosing bags must be packaged and storedinside an airtight bag or another low-moisture environment. This ishighly impractical at most jobsites where concrete is being mixed foruse. One humid night can ruin thousands of pounds of additives, if notstored properly at the jobsite.

Another problem associated with such prepackaged additives, is that thedissolvable packaging disintegrates so rapidly, that the additives heldin the packaging never have the opportunity to disperse before they passinto the mixture. Again, the result is that the additives tend to clumptogether and remain clumped during the mixing process. As a consequence,extra mixing is needed to ensure that the clumps are broken and that theadditives have had the opportunity to disperse evenly throughout themixture.

A need therefore exists for an improved packaging system for fibers andadmixture materials that can be thrown directly into a cementitiousmixture, where the package disperses its contents slowly and evenly, yetwherein the packaging completely dissolves. This need is met by thepresent invention as described and claimed below.

SUMMARY OF THE INVENTION

The present invention is a dissolving dosing bag for fiber or otherconcrete admixtures that is made from a dissolvable starch-based filmmaterial. When the dissolving dosing bag with its contents areintroduced into a mixture that uses water as an ingredient, and which isagitated for a period of time, the dissolving dosing bag dissolves at aparticular rate such that the fiber or other concrete admixtures arereleased into the mixture in an even manner.

The dosing bags are made in a chain. In this manner, any number of thedosing bags can be removed from the chain for use. The remaining dosingbags can be retained for later use. The dosing bags are each made from astarch-based film material that can dissolve in water. The film materialis formed into a tube structure. Part of the tube structure is filledwith fibers or admixture. While the tube structure is being partiallyfilled, a section on the interior of the tube structure is shielded fromcontamination. This is done either with a fold or with the use of aphysical barrier. After the partial filling, the tube is heat sealedclosed in the area that was previously shielded. The shielded area isclean of contaminants and enables a high-quality seam to be formed. Theshielding, filling, and sealing process is repeated multiple times tocreate the chain of dosing bags.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference is madeto the following description of an embodiment thereof, considered inconjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of an exemplary embodiment of a chain ofdosing bags;

FIG. 2 is a schematic of a pouch packaging machine that produces thechain of dosing bags shown in FIG. 1;

FIG. 3 is a cross sectional view of a section of continuous tubestructure containing a protective fold;

FIG. 4 is a cross sectional view of the segment of FIG. 3 with the foldremoved;

FIG. 5 is a cross sectional view of a section of continuous tubestructure protected by a shield; and

FIG. 6 is a cross sectional view of the segment of FIG. 3 with theshield retracted.

DETAILED DESCRIPTION OF THE INVENTION

Although the present invention dosing bag system can be embodied in manyways, the illustrations selected show only a few of the possibleembodiments. These embodiments are selected in order to set forth thebest modes contemplated for the invention. The illustrated embodiments,however, are merely exemplary and should not be considered a limitationwhen interpreting the scope of the appended claims.

Referring to FIG. 1, a dosing bag chain 10 is shown. The dosing bagchain 10 is comprised of multiple interconnected dosing bags 12. Each ofthe dosing bags 12 is made from a starch-based water dissolvable film14. For each of the dosing bags 12, the dissolvable film 14 is heatsealed around a volume of dry additive material 16. The dry additivematerial 16 can be fibers or any other dry or powdered admixturematerial that a person may want to add to a cementitious mixture.

The dissolvable film 14 used to make the dosing bag chain 10 is ahydroscopic plastarch material PSM. Several formulations of such PSMmaterials are commercially available in the marketplace. The compositionof a preferred PSM is described in U.S. Patent Application PublicationNo. 2008/0153958 to Ding, entitled Substantially CompletelyBiodegradable High Starch Polymer, the disclosure of which isincorporated into this specification by reference.

The dosing bag chain 10 is made by heat sealing long seams 18 andlateral seams 20 between and around deposits of the dry additivematerial 16. This creates sealed pockets 22 within each dosing bag 12that isolate the dry additive material 16. The pockets 22 defined byeach dosing bag 12 preferably hold less than 0.5 pounds of additivematerial 16 and may be so small that they hold only one or two ounces.During manufacturing, the dosing bags 12 are interconnected into largedosing bag chains 10. The dosing bags chains 10 are then packaged inlarger boxes, such as a five pound box or a twenty pound box.

For example, suppose that a particular batch of cementitious materialrequires 16¾ pounds of reinforcement fibers for a particularapplication. Using the present invention system, the fibers can beprepackaged in ¼ pound dosing bags 12. Eighty such dosing bags 12 canthen be packaged into a twenty pound box. To meet the requirement, aworker needs to open the box and toss sixty seven dosing bags 12 intothe mix in order to precisely meet the 16¾ pound requirement withoutwaste. The remaining thirteen remaining dosing bags 12 are saved forlater use. Since the dosing bags 12 are tossed whole into a mixer, thereis no labor wasted in measuring and dumping the fibers. Furthermore,since the dosing bags 12 are never opened by the worker, there is nodanger of chemical contamination or inhalation hazards from the additivematerial 16.

The addition of multiple small dosing bags 12 into a mixer, rather thanthe addition of a few large bags greatly increases the thoroughness atwhich the additive material 16 is dispersed throughout the mixture. As aresult, the likelihood that additive material 16 clumping will occur isgreatly reduced.

The dissolvable film 14 is heat sealed along the long seams 18 andlateral seams 20 that define the edges of each of the dosing bags 12 ina dosing bag chain 10. However, the dosing bags 12 are often filled withfine fibers or with fine powders. As the dosing bags 12 of dissolvablefilm 14 are filled, static often causes the fine powders to adhere tothe dissolvable film 14. As a result, the dissolvable film 14 becomescontaminated. This contamination on the dissolvable film 14 can preventthe dissolvable film 14 from properly being heat sealed along a lateralseams 20. As a result, the lateral seam 20 between the dosing bags 12can leak after the heat bonding process.

Referring to FIG. 2 in conjunction with FIG. 1, a method ofmanufacturing the dosing bag chain 10 is described that eliminates theproblem of film contamination and ensures proper heat sealed seams. InFIG. 2, a vertical pouch packaging machine 25 is provided. Two rolls 26,27 of dissolvable film 14 are provided. Both rolls 26, 27 pass throughvertical seamer 28 that join the dissolvable film 14 together alongcommon long seams 18. This creates a continuous tube structure 30 fromthe dissolvable film 14. It will be understood that a continuous tubestructure 30 can be made from a single roll of dissolvable film 14,provided the film is shaped into a cylinder and sealed along the onelong seam. Regardless, a continuous tube structure 30 of dissolvablefilm 14 is presented.

PSM film materials have a tendency to generate static charges as theyare pulled off the rolls 26, 27 and travel through the guides of thevertical pouch packaging machine 25. Consequently, any fine particulatematter floating in the air near the dissolvable film 14 has a tendencyto cling to the dissolvable film 14. The bottom of the continuous tubestructure 30 is initially heat sealed closed. This initial bottomlateral seal can be made in a contaminant free environment. However,subsequent lateral seals 20 must be made in an environment that ispolluted with the dry additive material 16 being used to fill the dosingbags 12.

The vertical pouch packaging machine 25 has a fill chamber 32. In thefill chamber 32, a predetermined volume of dry additive material 16 isreleased into the continuous tube structure 30. The dry additivematerial 16 passes into the continuous tube structure 30 through a fillconduit 34.

Prior to the dry additive material 16 being released, the continuoustube structure 30 passes through a folding mechanism 36. Referring toFIG. 3, it can be seen that when the continuous tube structure 30 passesinto the folding mechanism 36, the folding mechanism 36 creates a shortinvaginated fold 40 in the dissolvable film 14. The fold 40 isessentially S-shaped. After the fold 40 is created, a volume of dryadditive material 16 is deposited into the continuous tube structure 30.Referring to FIG. 4 in conjunction with FIG. 3, it will be understoodthat as the dry additive material is deposited, the exposed interiorsurfaces 42 of the tubular structure become contaminated with dust fromthe dry additive material 16. The presence of the contamination wouldprevent the dissolvable film 14 from being sealed together properlyabove the dry additive material 16.

Referring to FIG. 4 in conjunction with FIG. 3, it can be seen thatafter the dry additive material 16 is deposited, the fold 40 in thecontinuous tube structure 30 is undone. This creates a clean zone 44 onthe interior of the continuous tube structure 30 that is notcontaminated by the dry additive material 16. Returning to FIG. 2, itcan be seen that continuous tube structure 30 then passes into a lateralheat sealer 46 that creates the lateral seals 20 the continuous tubestructure 30, therein creating a dosing bag 12. The lateral heat sealer46 can be many commercial plastic sealing machines. A preferred machineis the Model PSF-400 impulse heat sealing machine made by the ClevelandEquipment & Machinery Company of Memphis, Tenn. The lateral seam 20 ismade across the clean zone 44. As such, the lateral seam 20 is made freefrom contamination. The result is a high quality lateral seal 20 that isconsistent between each of the dosing bags 12 in the dosing bag chain10.

Each lateral seam 20 is made wide enough to serve as the top seal of onedosing bag and the bottom seal of the next subsequent dosing bag. Eachlateral seam 20 then passes through a perforator 48, which perforatesthe lateral seam 20 so that the dosing bags 12 can be readily separatedwithout disrupting the integrity of the dosing bags 12.

The fold 40 formed in the dissolvable film 14 is only one way to protecta section of the dissolvable film 14 from contamination. Another methodis to use a shield barrier during the fill process. Referring to FIG. 5and FIG. 6, it can be seen that a protective barrier 50 can bemechanically applied to the interior surface 42 of the continuous tubestructure 30 as the dry adhesive material 16 is being deposited. Afterthe dry adhesive material 16 is deposited, the protective barrier 50retracts. This leaves a clear zone 52. The clear zone 52 can then passinto the lateral heat sealer 46, where the clear zone 52 is set into alateral seam 20.

It will be understood from FIG. 2 that pouch packaging machine 25creates the chain 10 of dosing bags 12. The dosing bags 12 each have thesame volume of admixture material. However, the volume can bepreselected on the pouch packaging machine 25. Provided the dosing bags12 are kept dry, each of the dosing bags 12 in the chain 10 remainsintact and the contents of each dosing bag 12 are confined. The dosingbags 12 are separated from the chain 10 to be added to a mixer 55.However, all the dosing bags 12 are not added simultaneously. Rather,the dosing bags 12 are added to a mixer one or a few at a time so thatthe dry additive material 16 are released over a prolonged period oftime. This relative slow release of the dry additive material 16 isoccurring during the mixing of the cementitious material. As a result,the admixture materials 14 are provided with the opportunity to bethoroughly dispersed throughout the cementitious mixture without anyclumping.

Due to the dissolvability of the dosing bags 12, the dosing bags 12 willcontinuously release their contents over a span of about thirty secondsto ninety seconds. At the end that period of time, the dosing bags 12dissolves to a point where they lose all structural integrity and all oftheir contents are released.

In the mixer 55, there are moving agitators and mixing occurs fairlyrapidly. A dosing bag 12 that releases material in a sixty-secondtimeframe enables the material being dispensed to fully intermixthroughout the cementitious mixture. Furthermore, since each dosing bag12 releases its contents over this prolonged period of time, there areno clumps or balls of material that can pass through the mixer 55without being properly integrated.

It can be seen from the foregoing discussion that the present inventionsolves most of the problems encountered in the prior art practice. It isbelieved that the operation and construction of the present inventionwill be apparent from the foregoing description. While the method anddevice shown and described have been characterized as being preferred,it will be obvious that various changes and modifications may be madetherein without departing from the spirit and scope of the invention asdefined in the claims.

What is claimed is:
 1. A method of manufacturing a dosing bag containingdry additive material for use in a cementitious mixture, said methodcomprising the steps of: providing a film of material that can dissolvein water; forming said film into a tube structure, wherein said tubestructure has an interior surface; filling part of said tube structurewith said dry additive material; shielding a clean section of saidinterior surface during said step of filling to prevent said cleansection from becoming contaminated with said dry additive material; andheat sealing said tube structure closed in said clean section to createa lateral seam.
 2. The method according to claim 1, further includingthe step of perforating said lateral seam.
 3. The method according toclaim 1, wherein said film has two long edges and wherein said step offorming said film into a tube structure, further includes heat sealingsaid two long edges together into a long seam.
 4. The method accordingto claim 1, wherein said film is supplied on two separate rolls and saidstep of forming said film into a tube structure further includes heatsealing said film from said two separate rolls together along longseams.
 5. The method according to claim 1, wherein said step ofshielding a clean section of said interior surface includes creating aninvaginated fold in said tube structure prior to said step of filling.6. The method according to claim 1, wherein said step of shielding aclean section of said interior surface includes placing a barrier oversaid clean section prior to said step of filling.
 7. A method ofmanufacturing a chain of dosing bags, wherein each of said dosing bagsin said chain contains a volume of dry additive material, said methodcomprising the steps of: i. providing a film of material that candissolve in water; ii. forming said film into a tube structure, whereinsaid tube structure has an interior surface; iii. shielding a cleansection on said interior surface; iv. filling part of said tubestructure with said dry additive material; v. heat sealing said tubestructure closed in said clean section to create a lateral seam and forman dosing bag having said dry additive material isolated therein; andrepeating steps ii, iv and v to create said chain of dosing bags.
 8. Themethod according to claim 7, further including the step of perforatingsaid chain between each of said dosing bags.
 9. The method according toclaim 7, wherein said film has two long edges and wherein said step offorming said film into a tube structure, further includes heat sealingsaid two long edges together into a long seam.
 10. The method accordingto claim 7, wherein said film is supplied on two separate rolls and saidstep of forming said film into a tube structure further includes heatsealing said film from said two separate roles together along longseams.
 11. The method according to claim 7, wherein said step ofshielding a clean section of said interior surface includes creating aninvaginated fold in said tube structure.
 12. The method according toclaim 7, wherein said step of shielding a clean section of said interiorsurface includes placing a barrier over said clean section during saidstep of filling.
 13. A method of introducing a required weight ofadditives to a cementitious mixture in a mixer, said method comprisingthe steps of: creating a chain of interconnected dosing bags joinedtogether along perforated seams that enable each of said dosing bags tobe selective separated from said chain, wherein each of said dosing bagsis filled with a unit weight of said additives that is a whole numberderivative of said required weight, and wherein each of said dosing bagsis formed from film that is dissolvable in water; separating a pluralityof said dosing bags from said chain, wherein said second weight of saidadditives in said dosing bags separated from said chain add up to equalsaid required weight; adding dosing bags separated from said chain intosaid mixer with said cementitious material, wherein each of said dosingbags separately dissolves and releases said additives, and wherein saidmixer distributes said additives throughout said cementitious material.14. The method according to claim 13, wherein said step of creating achain of interconnected dosing bags includes the sub-steps of: formingsaid film into a tube structure, wherein said tube structure has aninterior surface; heat sealing lateral seams in said tubular structureto form interconnected bags; and filling said bags with said dryadditive material to form said dosing bags.
 15. The method according toclaim 14, further including the substeps of: shielding clean sections onsaid interior surface; heat sealing said tube structure closed in saidclean sections to create said lateral seams.
 16. The method according toclaim 13, wherein said step of creating a chain of interconnected dosingbags includes forming dosing bags that each hold between one ounce andone pound of said additives.
 17. The method according to claim 13,wherein said step of creating chain of interconnected dosing bagsincludes creating dosing bags with heat sealed seams.